Some people are just not celebrities and handle fame in a pissy manner. Albert Einstein was angry about being famous, for example. Not everyone is an attention whore. That might make him appear more harsh than he actually is in person, much like Ellison. A lot of people like that are walking PR disasters, but are actually nice people to meet personally.
Moore seems to be grumpy about the movies getting made, and that's his right, even if he let it happen by signing a contract years ago. People do make mistakes, you know. He hasn't really been overly critical, but he's also not fawning over other people making different versions of his stuff. It might seem a little selfish, but that's ok by me, especially if he is simply redirecting money towards charity.